Fault-tolerant sensing and monitoring communications bus system for agricultural applications

ABSTRACT

An agricultural communication system is provided that enables sensor-to-sensor link communications of peripheral farming devices (planters, fertilizer or pesticide applicators, etc.) so as to enhance diagnostics for locating system faults and blockages. The system also provides a means to operate with single-faults present with real-time diagnostics to the operator. The point-to-point communications also facilitates simplified installation by automatically determining the sensor addressing based on the physical connection of the sensors. Since the sensor-to-sensor daisy chain bus system is self-configuring there is no dependency on the sensor manufacturing data or sequential installation procedure to define the sensor address as required in other prior art systems. A dual power supply from each end of the looped bus with independent switching provides operation in the presence of single-faults, and a diagnostic mode combined with sensor power supply voltage measurements provides fault location.

CLAIM OF PRIORITY

The present application claims priority to International Application No.PCT/US2013/020464, filed on Jan. 7, 2013, which in turn claims priorityto and the benefit of U.S. Provisional Application No. 61/584,000, filedJan. 6, 2012, the disclosure of which is are hereby incorporated byreference in their entireties.

BACKGROUND OF THE INVENTION

It is often desirable for an equipment operator to know the rate andquantity of articles being dispensed by certain dispensing equipment.For example, farmers who use mechanized equipment to plant agriculturalproducts must know the quantity of seeds that are being dispensed by themechanized planting equipment in order to optimize crop production andyield in a given area. Often, a farmer must know the quantity of seedsbeing planted in each row by the mechanized planter in order to optimizeproduction or even if the seed tube planting device is blocked.

To provide rate, quantity, timing, total and blockage information tofarmers and other operators of equipment, a variety of sensors andsystems have been developed which are capable of detecting that anarticle has passed along or through a predetermined path and displayingarticle dispensing performance metrics (i.e. rate, quantity, timing,total and blockage). In the case of mechanized seed planting equipment,most of the detecting sensors utilize electro-optical transducers whichreceive a light beam transmitted across a seed tube which light beam isinterrupted or interfered with by the passage of seeds through the tube.Every time the light beam is interrupted or sufficiently diminishedbelow some predetermined threshold, a “seed event” is said to occur and,for each seed event, the sensors typically send a signal to a centralmonitor which adds a count to the total count and displays the totalcount and other information.

In one example agricultural control system disclosed in U.S. Pat. No.5,864,781 to White, there is described a multi-drop communications thathas single point wiring faults that typically cause this type of busstructure to fail or partially fail. This system appears to use a“unique ID code” for each sensor in the system but this feature resultsin a burden on configuring the monitoring system. The association ofthis ID with a sensor position is required during the installation ormaintenance of the system and hence is not a quick process since eachsensor has to be plugged in sequentially and the installer has to waiton the display to recognize the sensor before plugging in the next one.

Nonetheless, with the increase in complexity of the communicationssystem, there is a need to have enhanced diagnostics, fault-tolerantcommunication bus, and simplified installation.

SUMMARY OF THE INVENTION

In one example embodiment, an agricultural communication system isprovided that enables sensor-to-sensor link communications of peripheralfarming devices (planters, fertilizer or pesticide applicators, etc.) soas to enhance diagnostics for locating system faults. The system alsoprovides a means to operate with single-faults present with real-timediagnostics to the operator. The point-to-point communications alsofacilitates simplified installation by automatically determining thesensor addressing based on the physical connection of the sensors. Sincethe sensor-to-sensor daisy chain bus system is self-configuring there isno dependency on the sensor manufacturing data or sequentialinstallation procedure to define the sensor address as required in otherprior art systems. The dual power supply from each end of the looped buswith independent switching provides operation in the presence ofsingle-faults, and a diagnostic mode combined with sensor power supplyvoltage measurements provides fault location. The various embodiments ofa new communications bus system described herein actually reduces thenumber of wires and connections of the sensors needed in an overallmonitoring system.

In a related embodiment, a fault tolerant monitoring and communicationsystem is described herein that includes at least one peripheralelectronic control unit (ECU) adapted to control a dispensed productoutput from a product dispensing unit and at least one master controlmodule adapted to be communicate with the at least one peripheralelectronic control unit. The monitoring system also includes a controlarea network (CAN) communications bus configured to interconnect the atleast one peripheral ECU with the at least one master module; and afirst plurality of sensor units configured and operatively connected ina daisy chain configuration and then operatively coupled to said atleast one master module, each of said sensor units being connected inparallel with each other and to a ground line and to a power source oneither end of said daisy chain configuration in the monitoring system,each of said sensor units configured to have dual communication witheach other. In a related embodiment, the master control module isadapted to communicate with a second plurality of sensor units as wellas with an ISO11783 compliant virtual terminal device.

In this example embodiment of the monitoring and blockage communicationunit, the dispensed product unit is selected from the group consistingof a seed planter, a fertilizer unit, an herbicide unit and a pesticideunit. The master control unit is configured to receive a blockage signalfrom at least one sensor unit operatively coupled to a dispensingproduct unit.

In yet another embodiment, the fault tolerant communication systemdescribed above further includes a slave control module operativelycoupled to the CAN bus and configured to communicate with a thirdplurality of sensor units. In a related example embodiment, themonitoring system further includes a plurality of slave control modulescoupled to the CAN bus having operatively coupled thereto acorresponding at least one plurality of sensor units coupled in a daisychain configuration.

In yet another related embodiment, a master control module is configuredto communicate directly with an ISO 11783 compliant virtual terminal (asa user interface) without a seeder or fertilizer electronic control unit(ECU) with a single CAN bus connecting all of the blockage systemmodules and the virtual terminal together. This configuration alsomaximizes the total number of individual sensors which can be monitored.In this example embodiment, an air cart with a ground driven seed metercontrols the row dispensing unit and there are then only ECUs associatedwith the blockage monitoring system. In yet another related embodiment,although not shown, the master control module (and associated sensorloop or loops) is configured to communicate directly with virtualterminal to provide for a basic blockage monitoring system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a prior art monitoring system used in anagricultural application.

FIG. 2 is a schematic of a monitoring and communication system accordingto the invention.

FIG. 3 is a schematic of a subsystem of a monitoring and communicationsystem according to the invention.

FIGS. 4A-4B is a diagram of a state machine of the monitoring systemdescribed herein and a diagram illustrating a plurality of alivemessages in the different states and the transition between states ofthe monitoring system.

FIG. 5 illustrates a user interface display of a monitoring andcommunication system according to the invention.

FIGS. 6A-6C is an example of a dual communication failure between twosets of sensors in two directions and various associated user displaysof same according to the invention.

FIGS. 7A-7D is an example of a loop with 20 sensors in various states ofdual communication failure between sensors and in one or two directionsand various associated user displays of same.

FIGS. 8A-8B is an example of a dual sensor power problem between twosensors and associated user displays of same.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Following below are more detailed descriptions of various relatedconcepts related to, and embodiments of, improved systems for monitoringand communicating blockages in seeding, fertilizing, herbicide andpesticide spreading applications. In a related embodiment, themonitoring system is used in salt (or salt) spreading or other materialdeposition that can get blocked or clogged in a deposition system. Itshould be appreciated that various aspects of the subject matterintroduced above and discussed in greater detail below may beimplemented in any of numerous ways, as the subject matter is notlimited to any particular manner of implementation. Examples of specificimplementations and applications are provided primarily for illustrativepurposes.

Referring now to FIG. 1, there is shown an example of a previous sensorcommunication subsystem 100 of a monitoring and communication system,similar to a system described in U.S. Pat. No. 5,635,911 issued on Jun.3, 1997, entitled “Apparatus and Method for Monitoring an ArticleDispensing Device such as a Seed Planter and the like”, which is hereinincorporated by reference in its entirety. System 100 includes an arrayof sensors 110, coupled to a power bus 122, a ground line 124 and acommunications bus or lines 126 and 128 and a program in and out line130 for creating the daisy chain communication between sensors 110. Inthis example, power bus 122 is a 12V (volt) line while sensors 110 iscomprised of sensors 110-1, 110-2, 110-3 through sensor 110-N. One ofthe challenges with system 100 is that it does not wrap the end of acommunications bus 126 and power bus 122 around back to the originatingmodule. Typical communications and power bus structures use linear busarchitectures terminating after the last node. This creates a bus wherea single-fault wiring failure results in reduced functionality orcomplete communications failure.

In one example embodiment of a novel monitoring and communication systemdescribed herein, as shown in FIG. 2, a system 200 is made up of asingle or multiple modules, with 1 or 2 sensor loops per module, capableof assigning each loop to one of 2 different blockage groups (seeding orfertilizer in this configuration). This allows the system toindependently perform blockage calculations on two different types ofapplications at the same time.

In this example embodiment, an operate mode interaction of a seedingcontrol unit (S-ECU) and the monitoring system includes the steps of:

1. Transmit configuration (at start up)

2. Start system

3. Receive blockage information from any product deposition unit andAlarms; and

4. Stop system

In a related embodiment, the monitoring system describe herein alsoprovides enhanced diagnostic messages to aid in troubleshooting. If atany point the system status changes, the monitoring system will generatean alarm message that indicates the type of problem in the system. Inthis example embodiment, the S-ECU will then request a status of thesystem to determine the exact problem. There can only be one activealarm in the monitoring system at a given time, hence upon reception ofan alarm the S-ECU will acknowledge the alarm and store/display thealarm to the operator. Once an alarm is acknowledged in the monitoringsystem, the next highest alarm will be posted if any exists.

A list of alarms is provided in the system hardware and is associatedwith an Alarm Manager message or signal. This message is sent anytimethat an alarm generating unit has detected an alarm condition.Transmission of this message may be periodic or on change of an AlarmAction. The alarm bitfield is a bitfielded 16 bit value that canrepresent anything to distinguish an alarm that can be generated frommultiple sources. A non-zero bitfield will represent an occurrence ofthe alarm is present (Alarm On), and a 0 value represents no activeoccurrences of his alarm exist at this time (Alarm Off). Informationabout the alarm if applicable (optional) will be provided in the AlarmData. The Alarm Data and Alarm Bitfield are application and alarm numberspecific. This message is sent from the monitoring system (DCBS) to theS-ECU every one second if there is an Alarm engaged that has not beenacknowledged by the S-ECU. The S-ECU acknowledges the alarm by sendingan Alarm Manager Signal Response for that alarm ID. The intent of thismessage is to provide the S-ECU information of DCBS Alarm status. OneCAN Message is defined for every Alarm ID. After an Alarm is disengagedthe Alarm Message will be sent once to indicate that the alarm hascleared.

The sensor and communication architecture of the various embodiments ofthe invention allows for full system operation during a single-faultwiring failure. Referring again to FIG. 2, there is shown one exampleembodiment of a communications interface system 200 disposed between aseeder electronic control unit 202 (S-ECU) and a dispensed productblockage system, a portion of which is shown in FIG. 3 in sensor andcommunications power loop 300. The dispensed product in this exampleembodiment is a seed, such as corn or soybean. In a related embodiment,the dispensed product is selected from the group consisting offertilizer, pesticide, herbicide and any other agricultural product orsalt, sand or rock when used in commercial applications.

In this example embodiment, the dispensed product blockage systemincorporating system 200 and system 300 is configured to include up to 4modules and a total of 8 loops (8×54=432 total sensors). Each module caninterface a maximum of 2 sensor loops. In this example embodiment, themaximum number of sensors per loop is 54. In this example embodiment,system 300 is configured to monitor two separate channels: Seeding andFertilizer.

In this example embodiment, sensor numbering is designated by the orderof the sensors in the loop (until complete):

Loop 1: Sensor 1—Sensor N (Ex. Seeder position 1 to 40)

Loop 2: Sensor 1—Sensor N (Ex. Seeder position 41 to 80)

Loop 3: Sensor 1—Sensor N (Ex. Seeder position 81 to 120)

S-ECU unit 202 is responsible for mapping the Loop X and Sensor Naddress to the physical position of a sensor on the Seeding and/orFertilizer channel. This example embodiment shows a multi-module systemthat includes modules 204, 206 and 208 having coupled thereto sensorloops 214, 216, 218 and 220, each loop being comprised of a plurality ofsensors (about 40 sensors in this example) operatively connected to eachother in a daisy chain configuration. In this example embodiment, system200 has a total of 160 sensors. In module 204, the first module in thisexample system (Dj#1, Module Position=0) will be the dispensed productsystem master module. In this example embodiment, S-ECU unit 202 has twoCAN communication ports and is capable of communicating with a virtualterminal (VT) 230 via an ISO11783 standard. The dispensed productmaterial system in this example embodiment is located on a secondnon-ISO CAN Bus.

In a related embodiment, master module 204 is configured to communicatedirectly with an ISO 11783 compliant virtual terminal 230 (as a userinterface) without S-ECS unit 202 with a single CAN bus connecting allof the blockage system modules and virtual terminal 230 together. Thisconfiguration also maximizes the total number of individual sensorswhich can be monitored. In this example embodiment, an air cart with aground driven seed meter controls the row dispensing unit and there arethen only ECUs associated with the blockage monitoring system. In yetanother related embodiment, although not shown, master module 204 (andassociated sensor loop or loops) is configured to communicate directlywith virtual terminal 230 to provide for a basic blockage monitoringsystem.

Referring now to FIG. 3, there is shown a monitoring and communicationsystem 300 according to one example embodiment which includes an arrayof sensors 310 coupled to a power bus 322, a ground line 324 and acommunications bus 326. In this example embodiment, power bus 322 is a12V (volt) line, and sensors array 310 is comprised of sensors 310-1,310-2, 310-3 through sensor 310-N. One of the advantages of system 300is that it provides for complete end-to-end communications and power busloop for a fault-tolerant system. Further, full-duplex serialcommunications in two directions around a communications loop forfault-tolerant data communications is facilitated thereby providingcomplete system operation when any single fault occurs. In addition,there is a dual power supply source for fault-tolerant powerdistribution from both sides of the loop. This provides complete systemoperation when any single power wiring fault occurs.

In various embodiments and variations of system 300, sensor loopdiagnostics include module hardware adapted for switching the powersupply on and off from each end of the loop. In the instance, where asingle-fault data communications or power distribution fault occurs,system 300 provides its location. Where a double-fault datacommunications or power distribution fault occurs, system 300 providesthe location of the open points. With respect to individual sensordiagnostics, sensor power supply voltage monitoring and sensorLED-current for monitoring static optical blockage levels, as well as adiscrete Push-Pull physical layer transceiver are optimized for cost andperformance in an agricultural environment. Individual sensor-to-sensorlink communications and periodic messages are used to continuouslydetermine the communications health of the system. On-demand messagesare used to determine integrity of the power bus. This is shown in aLoop Status 340 and a Loop Power Test Result 350 messages from system300.

In a related embodiment, system 300 is used in a Seed Blockage SensingSystem such that the communication bus is used for communicatingblockage data when the Seed Blockage Sensing system detects a blockageof an overall seed distribution system. Blockage data is communicated onthe bus and then an alarm sounds (or any other warning signal) to advisethe user that a portion of an air seeder system or a portion of a rowplanter system is blocked. In this example embodiment, 3phototransistors and 3 photodiodes are used in the system to detectblockages such as when the planting tube becomes clogged or blocked orthe seed is blown out into the ground. Blockage data is communicated touser via the bus. In another example embodiment, multiple LEDs are usedopposite a single photodiode cell to detect blockages.

In another related embodiment, system 300 is used in a FertilizerBlockage System wherein the bus is applied to a sensor system detectingthe blockage of a granular fertilizer distribution system. Blockage datais communicated on the bus, which is eventually communicated to the userin real-time.

In yet another related embodiment, relating to a Seed Counting System,the bus is used in connection with a counting system which is monitoringseed dispensing row units. Seed counting and timing data is communicatedon the bus which is delivered to the user in real-time so thatadjustments can be made on a timely basis. In this example embodiment,the sensing element is an infrared LED with an associated light sensorto sense disruptions in the light beam. Seed count data and ground speeddata are also used to make real-time adjustments in a planting system(or a fertilizer or pesticide system).

Referring now to FIGS. 4A and 4B, there is shown a diagram of a statemachine 400 of monitoring system (DCBS) 200 and a diagram 450illustrating a plurality of alive messages in the different states andthe transition between states of monitoring system 200. In this exampleembodiment, all control modules (coupled to sensor rings) will wake-upin a NotReady state 402 and all initialization and the module positionsequence will start. When the module position sequence has successfullycompleted, monitoring system 200 will enter a Ready state 406 or aFailed state 404 and system 200 master module (such as master module204) will indicate this System State. If the Module Position sequencefails the state will change to Failed. Alive messages from master module204 will indicate the current System State; with this being the onlymodule which the S-ECU will communicate with in this example embodiment.If one or more modules are in Failed state 404, the entire system 200 isin a failed state and a diagnostics screen is optionally presentedindicating which of the modules are in the Failed state. Commandmessages are defined to get the detailed status of any of the moduleswithin the DCBS system. The DCBS system is designed to be able toself-initialize without any communication with the S-ECU. The last setconfiguration is stored in the DCBS and upon power up will configure andcheck against that configuration. The S-ECU is responsible for makingsure the configuration is set correctly. The S-ECU may query the DCBSfor its configuration to determine if changes are needed, or it can sendthe configuration on each power up. When configuration messages arereceived the DCBS will determine if the setting is different thanprevious and re-initialize if necessary. This will transition the stateback to NotReady 402 state until initialization has completed.

In the NotReady state, the DCBS will perform all initializations andstart up procedures based on its stored configuration. At completion theDCBS will transition into the Ready or Failed state. Duringinitialization, if the hardware configuration does not match the storedconfiguration, alarms will be generated. In ReadyState 406, the DCBSSystem is waiting for the System start message, which represents theinactive state of the system. Typically a lift switch is used totransition in and out of this state when the machine transitions from inand out of work. In a RunState 408, the machine indicates that it is inthe work state and will begin its blockage monitoring function andreport back any blocked rows (which correspond to any blocked dispensingproduct units). In the FailedState, there is an indication that afailure occurred during the initialization process while the DCBS was inthe NotReady state, thereby causing the module to enter a failed state.To transition out of the failed state, the DCBS system failure must becorrected and power cycled or a new module must come online.

Referring now to FIG. 5, there is illustrated an example embodiment of auser interface display 500 of a monitoring and communication systemaccording to the invention. Display 500 includes images of a Seed module504, having a set of sensor loops 506 and 508 coupled thereto, and aFertilizer module 510, having a set of sensor loops 512 and 514 coupledthereto. In another embodiment, modules are configurable to monitorother materials that can be deposited and can clog or block thedispensing units such as pesticides, herbicides, salt, rock, and sandand the like. Display also includes softkeys 520 and 522 for increasingand decreasing seed blockage sensitivity, respectively, as well assoftkeys 530 and 532 for increasing and decreasing fertilizer blockagesensitivity, respectively. The results are displayed as Seed Sensitivity520A and Fertilizer Sensitivity 530A as well as blockage detection foreach as 540 along with respective values for each measurement.

Referring now to FIGS. 6A-6C there is illustrated an example embodimentof a dual communication failure between two sets of sensors in twodirections (600A-600C) and various associated user displays (650A-650C)of same according to the invention. In particular, there is acommunication line open from B to A (marked by X) between sensor 42 and43 and a communication line open from A to B (marked by X) betweensensor 44 and 45. Note that where the sensor count has been set too low,the only one sensor fault/open is detected of 600A in display 650A. Asthe sensor count is increased to 4 as in 650B then the correct number offaults are detected. When the sensor count is increased to 6, 650Cindicates the correct number of faults detected as well as all of thesensors in the circuit that are affected by the faults/opens.

Referring now to FIGS. 7A-7D is an example of a loop with 20 sensors(700A-700D) in various states of dual communication failure betweensensors and in one or two directions and various associated userdisplays (750A-750D) of same. In particular, note that in 700A anddisplay 750A, the sensor count has been set too low, and only 10 sensorsare expected but 20 sensors are found and such is indicated in display750A as an error message and a fail state. In example sensor circuit700B, Loop #2 has 20 sensors (Seed in this example as the Fertilizerfeature is turned off) there is a communication line open from A to B(marked by X) between sensor 2 and 3 and a communication line open fromB to A (marked by X) between sensor 19 and 20. Although the seed sensorcount is still unknown and cannot detect the number of sensors, itappears from display 750B that both faults/opens are detected but thecorrect location is not detected. Since the circuit is not set to detectthe correct number of sensors in the loop, all of the sensors (seed orfertilizer or whatever material is dispensed) will be ignored by theblockage algorithm all of the sensors in the loop will be marked asblocked (see display 750B, Loop #2 is marked with an “X”). In examplesensor circuit 700C, there is a communication line open from A to B(marked by X) between sensor 18 and 19 and a communication line openfrom B to A (marked by X) between sensor 19 and 20. Although the seedsensor count is still unknown and cannot detect the number of sensors,it appears from display 750C that both faults/opens are detected but thecorrect location is not detected. Since the circuit is not set to detectthe correct number of sensors in the loop, all of the sensors (seed orfertilizer or whatever material is dispensed) will be ignored by theblockage algorithm all of the sensors in the loop will be marked asblocked (see display 750C, Loop #2 is marked with an “X”).

In example sensor circuit 700D, Loop #2 has 20 sensors (Seed in thisexample as the Fertilizer feature is turned off) with the correct countbeing reflected in a display 750D so as to be able to detect the correctnumber of sensors in the loop. In circuit 700D, there is a communicationline open from A to B (marked by X) between sensor 18 and 19. It appearsfrom display 750D all of the sensor are detected and that a fault/openis detected and the correct location is also detected. All of thesensors (seed or fertilizer or whatever material is dispensed) will beused in the blockage algorithm and all of the sensors in the loop willreport blocked status (see display 750D, Loop #2 is marked with a “Δ”),with the blockage occurring between sensors 58 and 59.

Referring now to FIGS. 8A-8B, there is shown an example embodiment of adual sensor power problem and communication failure between two sensorsand associated user displays of same. In particular, FIG. 8A shows 6sensors in circuit 800A (sensors 41-46) with the Seed sensor count setto 6 in Loop #2. A power line open (marked by X) is shown betweensensors 44 and 45 and another power line open (marked by X) betweensensors 45 and 46. All of the sensors (seed or fertilizer or whatevermaterial is dispensed) will be ignored by the blockage algorithm and allof the sensors in the loop will be marked as blocked (see display 850A,Loop #2 is marked with an “X”) while the Communication display will showan error and the Loop Power will show where the power line open is to befound.

Referring now to FIG. 8B, in this embodiment 6 sensors are shown incircuit 800B (sensors 41-46) with the Seed sensor count set to 6 in Loop#2 (and the Fertilizer feature turned off) with a power line open(marked by X) being shown between sensors 44 and 45. All of the sensors(seed or fertilizer or whatever material is dispensed) are properlydetected and counted (Sensor Count—OK); all of the sensors communicatingproperly (Communication—OK) and no Sensor Results are displayed. TheLoop Power display however detects the power open line between sensors44 and 45 in display 850B (see display 850B, Loop #2 is marked with a“Δ” between sensors 41-46).

The various embodiments described above include one or more aspects ofthe following: complete system operation is maintained when any singlefault occurs; sensor loop diagnostics provide information that can bepresented to the user to aid in fault location; individual sensordiagnostics provides information that can be presented to the user toaid in pending wiring and connector problems and in determining sensoroptics blockage level, which is representative of dirt accumulation ordamaged optics. In a related embodiment, a microwave sensor is usedinstead of an optic sensor to sense the product being dispensed (seed,fertilizer, pesticide and the like). In an example embodiment, the costof the UART transceiver is reduced from commercially available IC parts(CAN, RS-485, etc.) as the threshold voltage levels have more hysteresisthan commercially available IC parts. In the case of a single pointwiring short, the individual sensor-to-sensor communications linkprovides a fault-tolerant communications bus while prior artarchitectures would typically result in stopping all communications onthe bus.

In this example embodiment, the system user is presented withinformation from periodic messages to continuously monitor thecommunications health of the system. The user invokes on-demanddiagnostics to determine integrity of the power bus. The variousembodiments of the invention provide diagnostic and configurationmessages not found in prior art systems.

In various example embodiments of the blockage monitoring systemsdescribed herein, the virtual terminal device is a wireless devicecoupled to the CAN bus 9 or coupled directly to the master controlmodule. The virtual terminal device can also be selected from the groupconsisting of a tablet, a smartphone, and a notebook PC.

While the invention has been described in connection with certainpreferred embodiments, there is no intent to limit it to thoseembodiments. On the contrary, it is recognized that various changes andmodifications to the exemplary embodiments described herein will beapparent to those skilled in the art, and that such changes andmodifications may be made without departing from the spirit and scope ofthe present invention. Therefore, the intent is to cover allalternatives, modifications and equivalents included within the spiritand scope of the invention as defined by the appended claims.

What is claimed is:
 1. A fault tolerant monitoring and communicationsystem comprising: at least one peripheral electronic control unit (ECU)adapted to monitor product output from a product dispensing unit; atleast one master control module adapted to communicate with the at leastone peripheral electronic control unit, wherein the at least one mastercontrol module further includes sensor loop diagnostics; a control areanetwork (CAN) communications bus configured to interconnect the at leastone peripheral ECU with the at least one master module; and a firstplurality of sensor units forming a sensor loop configured andoperatively connected in a daisy chain loop configuration and thenoperatively coupled to the at least one master module, each of saidsensor units within the loop being connected to a ground line and to apower bus or source on either end of the daisy chain loop in themonitoring system, each of said sensor units further connected at afirst end of the sensor loop with a first communication line andconnected at a second end of the sensor loop with a second communicationline so as to have dual communication with the loop of sensors andindividual communication lines between each sensor unit, wherein powerto and communication between each of the sensor units is maintained uponoccurrence of one of a power loss or a communication line loss on thefirst or second end of the sensor loop, and wherein the sensor loopdiagnostics of the at least one master control module provides alocation of a wiring fault, power or communications of a plurality ofsensor loops having a fault in the one of the power and communicationlines in the at least one sensor loop.
 2. The fault tolerantcommunication system of claim 1, wherein the sensor loop diagnostics ofthe at least one master control module is configurable to detect one ofa sensor fault, an open power line and an open communication line. 3.The fault tolerant communication system of claim 2, wherein the sensorloop diagnostics is adapted to identify among a plurality of sensorloops, the location by sensor and sensor loop of one or more sensor orline faults.
 4. The fault tolerant communication system of claim 1,wherein the dispensing product unit is selected from the groupconsisting of a seed planter, a fertilizer spreader, an herbicidespreader and a pesticide unit.
 5. The fault tolerant communicationsystem of claim 1, wherein said master control unit is configured toreceive a blockage signal from at least one sensor unit operativelycoupled to the dispensing product unit.
 6. The fault tolerantcommunication system of claim 5, further comprising a slave controlmodule operatively coupled to said CAN bus and configured to communicatewith a third plurality of sensor units in a third sensor loop.
 7. Thefault tolerant communication system of claim 1, further comprising avirtual terminal device operatively coupled to the CAN bus and to saidperipheral ECU and said master control module.
 8. The fault tolerantcommunication system of claim 7, wherein the virtual terminal device iswirelessly coupled to the CAN bus.
 9. The fault tolerant communicationsystem of claim 1, wherein the at least one peripheral electroniccontrol unit is adapted to map each sensor unit and sensor loop byproviding each sensor unit an individual sensor address within eachloop.
 10. A fault tolerant communication and blockage monitoring systemcomprising: at least one master control module adapted to communicatewith and control a dispensed product output from a product dispensingunit, wherein the at least one master control module further includessensor loop diagnostics; a control area network (CAN) communications busconfigured to interconnect the at least one peripheral electroniccontrol unit (ECU) with the at least one master module; and a firstplurality of sensor units forming a sensor loop configured andoperatively connected in a daisy chain loop configuration and thenoperatively coupled to the at least one master module, each of thesensor units within the sensor loop being connected to a ground line andto a power bus or source on either end of the daisy chain loop in themonitoring system, each of said sensor units further connected at afirst end of the sensor loop with a first communication line andconnected at a second end of the sensor loop with a second communicationline so as to have dual communication with the loop of sensors andindividual communication lines between each sensor unit, wherein powerto and communication between each of the sensor units is maintained uponoccurrence of one of a power loss or a communication line loss on thefirst or second end of the sensor loop, and wherein the sensor loopdiagnostics of the at least one master control module provides alocation of a wiring fault, power or communications of a plurality ofsensor loops having a fault in the one of the power and communicationlines in the at least one sensor loop.
 11. The fault tolerantcommunication system of claim 10, wherein the sensor loop diagnostics ofthe at least one master control module is configurable to detect one ofa sensor fault, an open power line and an open communication line. 12.The fault tolerant communication system of claim 11, further comprisinga slave control module operatively coupled to said CAN bus andconfigured to communicate with a second plurality of sensor units in asecond sensor loop.
 13. The fault tolerant communication system of claim11, further comprising a slave control module operatively coupled tosaid CAN bus, wherein the master module and the slave module havecoupled thereto one or two sensor loops and are adapted to assign eachloop to one of 2 different blockage groups, thereby allowing the systemto independently perform blockage calculations on two different types ofapplications at the same time.
 14. The fault tolerant communicationsystem of claim 11, further comprising a virtual terminal operativelycoupled to the CAN bus and to said master control module.
 15. The faulttolerant communication system of claim 11, wherein the sensor loopdiagnostics are adapted to identify among a plurality of sensor loops,the location by sensor and sensor loop of one or more sensor or linefaults.
 16. The fault tolerant communication system of claim 10, whereinthe dispensing product unit is selected from the group consisting of aseed planter, a fertilizer spreader, an herbicide spreader and apesticide unit.
 17. A fault tolerant seed sensor or dispensed productmonitoring and communication system comprising: a first plurality ofsensor units forming a sensor loop configured and operatively connectedin a daisy chain loop configuration and then operatively coupled to atleast one master module, each of said sensor units within the sensorloop being connected to a ground line and to a power bus or source oneither end of the daisy chain loop in the monitoring system, each ofsaid sensor units further connected at a first end of the sensor loopwith a first communication line and connected at a second end of thesensor loop with a second communication line so as to have dualcommunication with the loop of sensors and individual communicationlines between each sensor unit, wherein power to and communicationbetween each of the sensor units is maintained upon occurrence of one ofa power loss or a communication line loss on the first or second end ofthe sensor loop, and wherein the sensor loop diagnostics of the at leastone master control module provides a location of a wiring fault, poweror communications of a plurality of sensor loops having a fault in theone of the power and communication lines in the at least one sensorloop.
 18. The fault tolerant communication system of claim 17, whereineach of the sensor units are adapted for communication in one or twodirections and are adapted for communication between sensors.
 19. Thefault tolerant communication system of claim 17, further comprising acontrol area network (CAN) communications bus configured to interconnectthe at least one master control module with a slave control module, saidslave module configured to communicate with a second plurality of sensorunits in a second sensor loop, wherein the master module and the slavemodule have coupled thereto one or two sensor loops and are adapted toassign each loop to one of 2 different blockage groups, thereby allowingthe system to independently perform blockage calculations on twodifferent types of applications at the same time.
 20. The fault tolerantcommunication system of claim 19, further comprising at least oneperipheral electronic control unit (ECU) adapted to monitor a dispensedproduct output from a product dispensing unit and said ECU beingoperatively coupled to said CAN bus, wherein the at least one peripheralelectronic control unit is adapted to map each sensor unit and sensorloop by providing each sensor unit an individual sensor address locationwithin a loop.